Engine designs may include various features that serve various purposes. One example may be open-deck engine block design wherein a space is left between the cylinders and the main body of the engine block. Open-deck advantages may include lower cost, use of high-strength aluminum alloys, thinner block casting sections, better cooling, lighter weight, and easier removal of the die from the mold when the block is die cast.
Another example engine design feature may be to provide an engine knock sensor coupled with an engine controller. When engine timing is too far advanced knocking, or pinging, may occur, but when the timing is too far retarded performance may be compromised. A knock sensor may be used to cause the engine to run with the ignition timing as far advanced as possible but without knocking. An engine controller may advance the timing until the knock sensor detects knocking. Then the controller may retard the ignition timing just enough for the knocking, or pinging, to stop. In addition, or alternatively, with turbocharged engines, the controller may send signals to a wastegate to lower turbo boost pressure until the knocking subsides.
The inventors herein have recognized a problem with knock sensor effectiveness when used with open-deck design engine blocks. Since knocking may occur when the piston is a few degrees from the TDC position, it may be helpful to have the knock sensor as close as possible to the top portion of the cylinder where the knock occurs. But the open space around the cylinders in an open-deck block may create a longer path for the knock, or pressure, signal to travel. Additional damping from traveling longer may weaken the signals and may increase the noise to signal ratio.
Modifications to the open space around the cylinders in open-deck engine blocks have been proposed. For example U.S. Patent Publication 20100050433 provides a processing method, and processing jig for cylinder blocks to avoid deterioration in the cylinder bore circularity during processing. The jig includes pressing members having wedge surfaces containing pressing portions to press on an outside of the cylinder wall from within the open space while finish processing is performed within the cylinder bore on the opposite side of the cylinder wall.
The inventors herein have recognized a number of shortcomings with this approach, for example, the pressing members are only effective as a countering force during cylinder block processing, and not during engine operation. The reference fails to address the shortcomings of the elongated signal path taken by knock signals due to the open space around the cylinders as recognized by the inventors herein.
Embodiments in accordance with the present disclosure may provide bridging to the open space between the cylinder and the side wall of the engine block which may also be in close proximity to the cylinder head and to the decking surface. In this way the knock signal path is made much shorter. In this way signal integrity and improved engine control may be accomplished.
Embodiments in accordance with the present disclosure may provide an engine knock monitoring system that may include an engine block including an engine block body and a cylinder wall defining at least a portion of a combustion chamber. A space may be defined between a top of the cylinder wall and a top of the engine block body. An engine knock sensor may be mounted to the engine block. A pressure pulse transmissive element may be disposed in the space and may be disposed in contact with an outside surface of the cylinder wall and an opposite inside surface of the engine block body. In this way, pulses of pressure, from engine knocking may be effectively transmitted from the cylinder wall to the engine block body to be sensed by the engine knock sensor.
Other example embodiments may provide a system for an engine. The system may include an open deck design engine block including: an engine block body, a cavity in the engine block body, a cylinder wall disposed within the cavity coupled at a first side thereof to a cavity base and extending from the cavity base to a second side, the cylinder wall may define at least part of a combustion chamber on an inside thereof. A space may be located between the cylinder wall and the second side of the engine block body. An engine knock sensor may be coupled with the engine block body, and a knock impact transmissive block may be secured in the space. In this way, the space may not cause any impact signal delay or degradation.
Other example embodiments may include an engine knock signal transmissive element that may include a substantially solid block sized and shaped to fit within a space between a cylinder wall of a combustion chamber and a body of an engine block. To fit in the space the block may have a first side that conforms to the shape of a first contour located on the outside surface of the cylinder wall, and a second side that conforms to the shape of a second contour located on the inside surface of the engine block. In this way, the engine knock signal transmissive element may be used to facilitate efficient transmission of engine knock signals from a combustion chamber to a knock sensor.
It is understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.